1. Field of the Invention
The present invention relates to an imaging device and a focus control method.
2. Description of the Related Art
In recent years, with an increase in the resolution of solid-state imaging elements, such as a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor, a demand for a digital still camera, a digital video camera, a mobile phone, such as a smart phone, and an information apparatus with an imaging function, such as a personal digital assistant (PDA; a portable information terminal), has been increased rapidly. In addition, the above-mentioned information apparatus with an imaging function is referred to as an imaging device.
Some of the imaging devices use a phase difference auto focus (AF) system as a focus control method which detects the distance to a main object and focuses the imaging device on the object.
WO2013/047111A discloses a technique which prepares a small amount of correction data for the amount of defocus of each imaging lens and can perform high-accuracy focus control using the phase difference AF system, regardless of the type of imaging lens, in a case in which an imaging device using the phase difference AF system is a lens interchangeable type.
An apodization filter (hereinafter, referred to as an APD filter) has been known as an optical filter for improving the quality of an image that is out of focus, that is, a so-called blurred image. When the APD filter is used, it is possible to smooth the contour of a blurred image.
JP1998-268382A (JP-H10-268382A) and JP2011-221120A disclose an imaging device in which an APD filter can be inserted into and removed from the optical axis of an imaging lens.